(1) Field of the Invention
The present invention relates to surface coverings comprised of synthetic materials. More specifically, the present invention is directed to methods for the manufacture of composite vinyl sheet material particularly well suited for use as floor or wall coverings. Accordingly, the general objects of the present invention are to provide novel and improved materials and methods of such character.
(2) Description of the Prior Art
The field of technology related to the manufacture of synthetic surface coverings has long strived to imitate, in as realistic a manner as possible, the appearance of natural decorative elements such as wood, marble, stones, bricks, etc. Thus, present day manufacturing techniques for use in the preparation of synthetic surface coverings are to a large extent directed toward the achievement of either the illusion of relief or an actual relief in the surface of the material.
In the introductory portion of the present applicant's U.S. Pat. No. 3,905,849 issued Sept. 16, 1975, the disclosure of which is incorporated herein by reference, several prior art processes for the manufacture of sheet material having a textured wear surface are discussed. The invention of U.S. Pat. No. 3,905,849 relates to the printing of a decoration on the verso of a sheet of transparent synthetic material followed by application of at least one discontinuous intermediate layer of an appropriate paste over selective regions of the printed sheet; the paste matching at least part of the decoration and being applied in regions which are to form the raised portions of the surface of the desired textured end product. Subsequently, in the present applicant's prior invention, the transparent sheet is laminated to a support in such a manner that the verso of the transparent sheet faces the support and the transparent synthetic sheet material thus flows into the cavities defined by the intermediate layer of paste. This prior technique results in the discontinuous intermediate layer applied to the verso of the transparent sheet causing formation of a relief on the recto of the finished product. The product produced by the present applicant's prior invention is thus a transparent sheet which comprises a wear layer overlying a decoration which in turn covers the discontinuously applied intermediate material used to achieve the relief effect; the composite comprising the transport sheet and intermediate layer being bonded to a support comprising one or more layers.
The necessity of printing a decoration on the transparent sheet has, however, been found to cause certain manufacturing difficulties. These difficulties may be attributed to the fact that the printed sheet is deformed when the assembly, defined by the sheet with the decoration thereon and the discontinuous intermediate layer of paste providing the relief, is heated in a gelation over prior to lamination to the support.